Apparatus for directive signaling



Nov. 10, 1925.

R. A. FESSENDEN FOR DIRECTIVE SIGNALING APPARATUS Original Filed Dec. 26 1918 2 Sheets-Sheet 1 Nov. 10, 1925. 1,561,441

R. A. FESSENDEN APPARATUS FOR DIRECTIVE SIGNALING Original Filed Dec. 26. 1918 2 Sheets-Sheet 2 Patented Nov. 10, 1925.

UNITED STATES REGINALD A. FESSENDEN, F NEWTON,

MASSACHUSETTS, ASSIGNOR TO SUBMARINE SIGNAL COMPANY, OF POBTLAND, MAINE, A CORPORATION OF MAINE.

APPARATUS FOR DIRECTIVE SIGNALING.

Original application filed December 26, 1918, Serial No. 268,231.

Divided and this application filed May 28, 1920. Serial No. 384,993.

To all whom it may concern:

Be it known that I, REGINALD A. FESSEN- DEN, of Newton, in the county of Middlesex and State of Massachusetts, a citizen of the 6 United States, have invented a new and use ful Improvement in Apparatus for Directive Signaling, of which the following is a specification. This application is a division of application Serial No. 268,231, filed De- 10 cember 26, 1918, which was a continuation of application Serial No. 186,627, filed August 16, 1917, in so far as the parts are alike.

My invention relates to the transmission and receipt of energy and more particularly to signaling and still more particularly to directional signaling, especially the location of submarines and submarine signaling stations and also of aeroplanes.

The object of my invention is to improve the acoustic efiiciency of the sending and receiving energy and more especially to improve the eificiency of signaling and still more to improve the efficiency of apparatus 2 and methods for locating submarine signa1- ing stations and submarines. It may be used on shipboard or otherwise.

Figure 1 accompanying this specification illustrates, partly diagrammatically, apparatus adapted for carrying outmy invention.

Figure 2 is a diagram described below.

In Fig. 1. 33 is a vessel, for example of the destroyer type, and 30, 31 and 32 are the compartments of the forepeak or oil tanks of the torpedo destroyer, though the may be fluid containers otherwise located: according to circumstances.

11 and 12 are sound receiving devices of any suitable kind; for example microphones or stethoscopes or electromagnetic receivers and preferably oscillators of the kind described in United States Patent No. 1,167 366. I shall hereinafter refer to these, generally speaking, as sound detectors.

These oscillators are shown as located on board ship and are placed in any suitable position with reference to each other, either side by side, or, as shown, back to back in the same tank or adjacent fluid-containing tanks, and preferably have their faces perpendicular to the skin of the ship. As shown, they are separated by the soundinsulating screen 13, 14, of any kind, being attached to each other and to it by the bolts 15. 16, which may be insulated therefrom by soft rubber or lead in a known way.

Both oscillators and sound screen are mounted on a pivot 29 and can be rotated by any suitable means, as for example by the handle 17.

The sound screen 13, 14 may be constructed and shaped in any suitable way to produce the desired result; for example at the end 14 the sound screen is shown in curved shapeso as to shield to a greater extent than at the end 13.

I 1preferso to shape the sound screen 13, 14 t at a sound coming from a given angle and striking the oscillators will be heard with the same relative intensities and phases as a sound coming from the same angle and striking the head of a human being.

The shape of the sound screen to accomplish this is best determined by experiment, the shape being varied until a person listening in on telephone receivers attached to the oscillators will obtain the same change in relative sound intensities in the two receivers when the oscillators are turned to a certain angle as he obtains when he turns his head through the same angle.

An important point to note is that when the oscillators are used in a different medium from air, for example in water, the distance of the oscillators apart should preferably bear the same relation to the velocity of sound in such medium, for example water, as the usual distance apart of the two cars of a human body bears to the velocity of sound in air. For example, if the distance between the ears is 8 inches and the velocity of sound in air is 1100 feet per second, then if the oscillators are immersed in water, in which the velocity of sound is 4400 feet per second, the oscillators should preferably be placed a little less than 3 feet apart. If the oscillators are placed further apart, as for example 10 inches, still further changes are obtained and the sound screen must be extended still further in order to obtain thedesired effect on turning: the oscillators around on their pivot 29.

18, 19. 20, 21 are leads from the oscillators to the indicators shown as telephone receivers 26, 27, which with the other appa.

rates may be located upon the bridge or other convenient place and are connected by the head hand 28, but are not electrically connected to each other.

33 and 34 are switches for opening or closing the lead circuits as desired.

22, 23 are adjustable capacities, and 24, 25 are adjustable inductances. These capacities and inductances have the function, in addition to their other functions, that by changing their relative values the phase of the sounds reaching the receivers 26, 27 can be altered without turning the oscillators on their pivot, or, if the oscillators are turned on their pivot, the change of phase may be increased or decreased.

For example, if a sound is received on the port how, the oscillators may be either turned by means of the handle 17 until the sound appears to come from a point perpendicular to and in front of the line joining the centres of the diaphragms of the two oscillators, the sound then being equally loud to both ears of the observer, and the angle through which the handle 17 is beirn moved may be measured and the exact direction of the sound may be thus determined. Or the oscillators may be left stationary and the condensers 22, 23, or inductances 2- 25, or both, adjusted until the sound appears dead ahead and the readings of the condensers and inductances taken and in this way the exact direction determined. Or both oscillators and condensers and inductances may be left stationary and the vessel turned until the sound appears to come in dead ahead and the bow is pointed in the direction of the source of sound.

The tanks 30, 31, 32 are preferably filled either with water or oil, and when the oil is used up, it is preferably replaced with water.

It is to be noted that 30, 31 and 32, are the oil tanks or water tanks, and that the chamber between oil tank 30 and the bow of the vessels, and the chamber between oil tank 32 and the stern of. the vessel are not oil or water tank chambers, and being filled with air may be called air chambers, and as such do not conduct sound to anything like the same extent as if they were oil tank chambers, and hence do not conduct sounds originating at the bow and stern of the vessel into the oil tanks 30, 31 and 32.

The insertion of the oscillators in fluidfilled tanks, for example forepeak tanks, or, as shown, in oil tanks, has the great advanta e that, as applicant has discovered, it one les the sound to be received nearly as well dead ahead as abeam.

For example, with the installation placed on the S. S. Devereaua' the distance at which it was possible to send and receive dead ahead was 31 miles as against 36 miles abeam. With the installation placed on the U. S. destroyer Aylwin the working distance dead ahead was 84% of that abeam.

Figure 2 illustrates diagrammatical tests made on an insulation of this general type, 3251 representing the vessel, the dotted line -11 representing the range obtained at different angles with oscillators installed in the skin of the ship and the full line 40 is corresponding range with the oscillator mounted in tank as shown above.

I have discovered that it 18 possible to still further increase the range dead ahead or dead astern by making the skin of the ship or the wall of the tanks or the chamber containing the sound receiver so that the index of refraction of the skin of the ship or the wall of the tanks relative to water is unity.

For example, the velocity of sound in water is approximately 4400 feet per scc-' end, while the velocity of sound in steel is approximately 17,000 feet per second. C011- scquently, sounds striking the skin of the ship at a small angle are totally reflected and do not enter the ship and affect the oscillators.

I have found, however, that by loading the skin of the ship so that the index of reiraction of the skin of the ship or the wall of the tanks relative to water is unity not only are water noises greatly lessened but also sound passes directly from the signaling station to the oscillator, almost as if the skin of the ship were not there.

One method by which I accomplish this toelcctrically weld, or otherwise suitably attach, lumps or disks or plates of lead or other suitable material, such as tungsten, to the inside of the skin of the ship, or to use 105 material such as zinc or tin or tin alloyed with lead, or to use a plate having holes punched in it. the holes being filled with iead or brass. Other arrangements may suggest themselves, but whatever the arrangement 0 used. it should be such as to make the index of refraction of the skin of the ship or the wall of the tanks relative to water equal to unity, and if weights are used, such as disks of lead, they should be close together, i. e. 115 the distance between any two adjacent ones should be approximately equal to less than a quarter wave length of the sound which is to be received.

This method is also of value as a method of eliminating high pitched sounds which it is not desired to receive, as sounds whose quarter wave length is less than the distance between the weights may be retracted while sounds of longer wave length will be trans- 125 mitted.

Other arrangements of ap aratus to accomplish this result and be wlthin the scope of my invention will occur to those skilled in the art.

ed With the two translating devices forbringing the current therein into phase, substantially as described.

2. In apparatus of the character described,

the combination of a plurality of receptors of Wave energy disposed about a common center, a detecting device, and means for brin ing the received ener into phase at the detecting device comprlsin connections from the detecting device to t e several receptors having time difference of energy traverse equal to the difference in time of arrival at the receptors to which they are connected, of wave energy passing in a certain direction across the center of receptors, substantially as described.

3. In apparatus of the character described, the combination of a lurality of micro phonic receptors of su marine sound disposed about a common center, an auditory detecting device, and energy transmitting paths between the receptors and the detecting device having provision for imposing on the transmitted energy time lag equal to the difi'erence in time of arrival of the received submarine sound waves at the receptors to which they are connected, substantially as described.

REGINALD A. FESSENDEN.

Certificate of Correction.

It is hereby certified that in Letters Patent No. 1,561,441, granted November 10, 1925, upon the application of Reginald A. Fessenden, of Newton, Massachusetts, for an improvement in Apparatus for Directive Signalinlg, an error appears n the printed specification requiring correction as follows: age 3, after line 36, insert the following as claims 4, 5, 6, 7, 8, 9, and 10:

43A method of measuring small time intervals, which consists in successively generating in a plurality of electrical circuits similar waves spaced by the time intervals it is desired to measure, adjusting the relative electrical length of such paths until the waves reach a definite point in said paths simultaneously, whereby the emtent of time intervals may be deduced from the necessary adjustment of the paths.

5. A compensator adapted for use with receivers of wave energy, comprising two auditory translating devices, one for each ear, and means for transmitting the wave energy from each receiver to the corresponding translating devices includseparate variable energy conducting paths connected with the said translating devices for bringing the oscillations therein info phase, substantially as described.

6. A compensator adapted for use with receivers of wave energy, comprising two auditory translating devices, one for each, ear, and means for transmitting the ware energy from each receiver to the caries 1oruling translating devices including separate manually adjustable energy conducting paths connected with the said translating devices for bringing the oscillations therein into phase, substantially as described.

7. A p-aratus for comparing the phase relation between u-aves generated in a pair 0 circuits, comprising means for generating similar waves in each circuit, means for translating such waves into audible effects, and means for varying the electrical constants of one of said circuits to shift the phase of the wave in such circuit relative to the 'wave in the other circuit.

8. Apparatus for locating a source of sound, comprising a pair of sound responsive current varying devices, a pair of electrical paths including said devices, means for varying the relative length of said paths, and means for comparing the current variations produced by said current varying devices in said paths.

9. Apparatus for binaura-l determination of the direction of travel of vibralions comprising two separated receivers of vibrations for respectively causing variations in two electric currents corresponding to the received vibrations, earpieces, one for each ear of the observer, energy transmitting connections between the respective receivers and earpieces, and adjustable means in one or more of such connections whereby the time of travel from one receiver to the corresponding earpiece can be varied with. respect to the time of travel from the other receiver to its corresponding earpiece.

10. Apparatus for the binanral determination of the direction of sound in water comprising two spaced electrical telephone transmitters, two earpieees, energy trans matting connections between the respective transmitters and earpieces, and adjust able means in one or more of snch connections whereby the time of ,travel from one transmitter to the corresponding earpiece can be varied with respect to the time of travel from the other transmitter to its corresponding earpiece. and that the said Letters Patent should he read with this correction therein that the same may conform to the record of the case in the Patentv Ofiice.

Signed and sealed this 15th day of December, A. D. 1925.

[SEAL] VVML A. KINNAN,

Acting Commissioner of Patents. 

